This invention relates to apparatus for the cutting of earth formations and, more particularly, to the mounting of drum-type cutters on mining machines.
Machines for cutting earth formations such as coal and other mineral deposits, rocky soil, etc., often employ rotary cutters comprising cylindrical cutter drums which carry pointed cutter bits. The cylindrical drums are connected to a rotary drive shaft which rotates the drums at the same time that the cutter is advanced against an earth formation to cut therethrough.
In some mining machines, for example, carrier arms extend forwardly from a vehicle body and carry a rotary cutter mechanism which rotates about a transverse horizontal axis. The cutter mechanism comprises a support housing and a drive shaft assembly rotatably mounted within the housing, and a series of longitudinally spaced cutter drums connected to the drive shaft assembly to be rotatably driven thereby.
Some of the cutter drums (outside drums) are located to the outside of the carrier arms and comprise one-piece cylinders which can be slid axially over the housing and suitably fastened in place. Others of the drums (inside drums) are located between the carrier arms. These inside drums cannot be conveniently removed in an axial direction and thus are usually formed of semi-cylindrical segments which can be separated radially to provide access to the support housing and drive shaft assemblies for maintenance.
It has heretofore been proposed to connect the segments of the inside drum by means of bolts oriented perpendicularly or orthogonally relative to the axis of rotation. Because of this orientation, however, the bolts are subjected to such intensive stress acting along the bolt axis, that the bolts often become stretched, thereby allowing the drum segments to separate. Consequently, work must be stopped in order to replace the bolts. Oftentimes, an operator simply removes the bolts and welds the semi-cylindrical members together. This latter practice avoids the bolt-stretching problem but greatly complicates maintenance operations since the drum can only be removed in an axial direction, thus requiring substantial dissemblage of the cutter mechanism.
It is, therefore, an object of the present invention to minimize or obviate problems of the type discussed above.
It is a further object of the invention to enable cutter drum segments to be removably fastened together while minimizing chances that the drum segments will separate during operation.
It is yet another object of the invention to enable cutter drum segments to be connected by bolt type fasteners while minimizing the stresses to which the bolts are subjected during cutter operation.